REF-168 · Jones et al., 2019 · Physiological Reports, · Paper

The Maximal Metabolic Steady State: Redefining the 'Gold Standard'

B+moderate evidenceMeasured on a mixed groupWritten before October 2026, being re-checked

Jones, Burnley, Black, Poole & Vanhatalo argue that critical power (CP), not the maximal lactate steady state (MLSS), is the true "gold standard" for the maximal metabolic steady state.

MLSS and CP are two widely used indices of the highest oxidative metabolic rate sustainable in continuous exercise and are often treated as synonymous; but methodological differences in how they are determined typically place MLSS at a somewhat lower power output or running speed than CP, and exercise at CP is sustainable for no more than approximately 20-30 min — the view the authors go on to dispute: in the body they report time to the limit at CP as highly variable (~15 to 40 min, occasionally up to ~60 min) and call the question of how long CP can be sustained ill-conceived (corrected 2026-10-12, full text).

That has led to the view that CP overestimates the "actual" maximal steady state.

The authors present evidence for the opposite: (1) as presently defined, MLSS naturally underestimates the actual maximal metabolic steady state; (2) CP alone marks the boundary between discrete intensity domains within which the dynamic cardiorespiratory and muscle metabolic responses differ profoundly.

Key Findings

MLSS typically sits at a somewhat lower power/speed than CP (abstract; no percentage is given)
The abstract cites "no more than approximately 20-30 min" at CP as the basis of the view the authors dispute; the full text reports time to the limit at CP as highly variable (~15 to 40 min, occasionally up to ~60 min) and calls the question of "how long" CP can be sustained ill-conceived (corrected 2026-10-12, full text)
The authors' position: MLSS, as defined, underestimates the maximal metabolic steady state; CP is the genuine boundary between exercise in which physiological homeostasis can be maintained and exercise in which it cannot
They urge that MLSS and CP stop being compared as if theoretically synonymous, and that CP be treated as the gold standard when the goal is to determine the maximal metabolic steady state
Both metrics may still have relevance for training and performance

Practical Application

Position paper, no new data: the leading CP group argues that critical power — not MLSS — is the true boundary of the maximal metabolic steady state; MLSS typically falls somewhat below CP because of how it is determined, time to the limit at CP is highly variable (~15-40 min, occasionally ~60 min) and the authors reject attaching a duration to it (corrected 2026-10-12, full text), and CP alone separates the intensity domains whose physiological responses differ profoundly. Use CP as the heavy-to-severe boundary; treat MLSS as a conservative estimate that sits below it.
Define the severe domain from CP, not from FTP: an interval meant as a VO2max stimulus must sit above CP, and an FTP-derived percentage may or may not be there for a given athlete (Inference from the paper's domain argument).
Not from this paper: a 3-min all-out test or a multi-trial CP model gives CP directly (REF-044); an FTP protocol gives a proxy that is not the domain boundary.
Long events are ridden well below CP — how far below depends on duration and fuelling (REF-145), not on a fixed percentage.

Limitations

Position paper — argument and selected evidence, no systematic review; the size of the MLSS-CP gap is not quantified in the abstract; "approximately 20-30 min" is the abstract's premise for a view the authors dispute, not their finding; the body reports ~15-40 min (occasionally ~60 min) across studies (corrected 2026-10-12, full text).

How this entry was checked and changed
Why this level

regraded 2026-09-27 from A: narrative position paper from the leading critical-power group, no systematic method, no meta-analysis

Content correction 2026-09-27
"CP > MLSS by ~5-10%" and "Exercise at MLSS: sustainable >30 min" -> not in the abstract (which says only "somewhat lower"); deleted.
Level A -> B+ (narrative position paper); Sport "swimming" -> general; Tier N/A -> mixed.
Cross-reference REF-162 (duplicate) -> REF-306.
Cross-references to duplicate stubs repointed to their canonical entries (REF-200->REF-024); the stubs were emptied on 2026-09-27.
Full text (checked 2026-10-12)
On average, CP has been reported to be ~7% higher than MLSS, with individual studies reporting 4%, 9%, 16%, 5% and 9% (cf. 1%, Keir et al. 2015) (full text).
MLSS is the highest speed or power at which blood lactate rises by no more than 1 mmol/L between minutes 10 and 30; lactate analysers typically have an error of 0.2–0.4 mmol/L, and the reliability of submaximal blood lactate measurement is 11–52% (full text).
Continuous exercise 10 W above MLSS produced a steady-state V˙O2 equivalent to ~90% V˙O2peak, which the authors describe as heavy-intensity behaviour (full text).
Correction: the entry states "Exercise at CP is sustainable for no more than approximately 20-30 min" as a finding; the paper presents this as the view it disputes and says time to the limit of tolerance at CP "is highly variable (e.g., range of approximately 15 to 40 min or occasionally up to ~60 min)" and that the question of "how long" CP can be sustained is "ill‐conceived" (full text).
The uncertainty band around a modelled CP can be reduced to approximately ± 3–5%; for a CP of 300 W with a standard error of 2%, the "real" CP lies between 294 and 306 W (full text).
For conventional CP testing, the shortest prediction trial should ideally last 2–3 min and the longest more than 10 but no more than 15 min; accuracy is satisfactory when the standard error is less than 5% of the mean for CP and less than 10% for W′ (full text).
In the 3-min all-out test, a "preferred cadence" that is too high (≥90 rpm) tends to underestimate Wʹ and overestimate CP, and the test should be repeated if V˙O2 reaches < 95% V˙O2max (full text).
Elite marathon runners have been estimated to sustain ~96% of their critical speed during competition (full text).